The instant invention is directed to a heated recording chamber. More particularly, the instant invention is related to a heated recording chamber suitable for use with high magnification microscopes.
Electrophysiological recording from single adult cells or colonies of cultured cells requires the use of high magnification microscopes. It is necessary that tissue recording chambers used with such microscopes fit on the microscope stage and be relatively thin so that the preparation under scrutiny is relatively close to the objective of the microscope. If the cells under study are too far from the objective lens, proper focusing of the microscope is hindered, if not impossible. The tissue recording chambers must also provide for the transmission of light through the preparation containing the cells so that the cells may be observed.
When a heated recording chamber is required, it is difficult to make the chamber both transparent and relatively thin so as to be usable with high magnification microscopes. Under normal operating conditions, the chamber is superfused with a physiological solution, providing a bath which must be maintained at a selected temperature. While it is possible to preheat the physiological solution prior to delivery to the chamber, this approach is not always effective because the solution cools as it enters the chamber, resulting in a temperature gradient across the chamber. The gradient can result in opposite ends of the chamber differing in temperature by as much as 3.degree. or 4.degree. C. All reactions are highly temperature dependent. Therefore reactions of 3.degree. to 4.degree. C. preclude consistent data recordation.
In view of constraints on the configuration of recording chambers, placing a heating element under the chamber to evenly heat the entire bath is precluded because such heaters are opaque and because such heaters have a thickness which interferes with fitting the recording chamber in the space available between the objective lens of the microscope and stage.
There are a number of systems currently available for heating tissue recording chambers; however, each of these systems has at least one drawback. A heater marketed by N. B. Datynar provides a thin, optically clear heating element and temperature controller. However, the Datynar device includes no special provisions for recording chambers and is generally used as an immersion heater with a small petri dish provided by the user. Photon Technology International, Inc. makes a microscope tissue chamber which employs an annular heating element which surrounds the recording chamber. Light passes through the opening in the annular heating element, but, in order to provide for light, the opening allows cooling of the tissue chamber contents, resulting in a temperature gradient from the outer edge of the chamber to the center thereof. This system is also very expensive, even without the power supply. A number of other systems, similar to the Photon Technology International, Inc. arrangement, are available; however, these systems have the same shortcomings.